Author(s)

Harsho Sanyal & Joseph Cataldo

Abstract

Climate change has led to triple digit temperatures globally, notably along the western coast of the United states. These changes have produced intense weather-related events such as fires and landslides. Green roofs are one strategy to mitigate these high temperatures. For this report, several studies were compiled, using data found from physical green roof models as well as on-site data from the Javits Center Green Roof. At the Javits Green Roof, an infrared camera was used to collect thermal images at various parts of the roof, to determine its effectiveness for thermal buffering. Off site, a rain simulator was used on model green roof and a control roof, to determine change in retention and peak runoff rate. The green roof was able to retain 2%–22% of rainfall and reduce peak runoff by 19%–28%. From the graph comparing roof temperatures, there were higher temperatures on the black top roof in comparison to the green roof, and the slopes of the lines indicated the mitigating effect of the green roof on heat waves. These models were also analysed with an infrared camera, which showed that green roofs can be, as much as 25°f cooler than their standard roof counterparts, providing valuable evidence for the usefulness of green roofs to combat heat waves. Runoff quality was experimentally measured using a green roof model, where nitrogen concentration is measured before and after to determine change in runoff quality. This concept is based on studies which claim that the addition of wood mulch to soil can reduce nitrogen content. This experiment revealed a 23% reduction in runoff nitrates for the wood-mulch treated soil, in comparison to a 6.5% reduction for the control roof. Furthermore, a mathematical model was used to determine the ceiling temperature of the Javits Center within 3%.

Keywords

green infrastructure, green roof, infrared camera, thermal buffering, runoff.